The present invention relates to a non contact type IC card, and more particularly to a non contact type IC card allowing the protection of data stored in the card and the prevention of data falsification.
A non contact type IC card performing data communication with an interrogator installed outside has been used conventionally. The examples include a ticket for ski lift, a seasonal ticket for the transportation and a prepaid card.
FIG. 7 is a block diagram schematically showing a basic structure of a conventional non contact type IC card 900. Conventional non contact type IC card 900 shown herein, which is an IC card performing data communication in a signal superposing manner, supplies power and transmits/receives information using a signal(s) having one or more frequencies received from the interrogator not shown.
Conventional non contact type IC card 900 as shown in FIG. 7 is an example of non contact type IC cards utilizing a single frequency and includes a tuning circuit 20, a rectifying circuit 21, an amplifying/demodulating circuit 22, a modulating/amplifying circuit 23 and an SP/PS conversion circuit 24.
Tuning circuit 20 includes a coil L functioning as an antenna and a capacitor C0. Rectifying circuit 21 rectifies a signal received at tuning circuit 20, thereby generates and supplies the power to each part of non contact type IC card 900.
Amplifying/demodulating circuit 22 amplifies and demodulates data Q from an interrogator received at tuning circuit 20. A signal output from amplifying/demodulating circuit 22 is SP-converted by SP/PS conversion circuit 24 and then is output to a main control circuit 2 described below.
With reference to FIG. 7, conventional non contact type IC card 900 further includes main control circuit 2 and a memory 1.
Main control circuit 2 processes a signal output from SP/PS conversion circuit 24. Main control circuit 2 generates data DA to be stored in memory 1 described below and designates a location (address) of memory 1 to which data DA is to be written.
Memory 1 includes normal data storage region B1 and data protection region B2. Memory 1 receives data DA via a data line L2 as well as an address signal AD via an address line L1 indicating an address (a location to which data is to be written) to which data DA is to be written. Here, data stored in data protection region B2 particularly requires security in order to guarantee a normal data communication and whose rewriting is inhibited. An example of such data is an ID number of an ID card holding the personal information.
In addition, main control circuit 2 reads data from designated region B1 or data protection region B2 of memory 1 according to the contents of data Q received from the interrogator and generates a response data A based on the read data. Response data A is PS-converted at SP/PS conversion circuit 24, processed at modulating/amplifying circuit 23 and then transmitted to the interrogator via coil L forming the antenna.
In conventional non contact type IC card 900, however, the rewriting (falsification) of stored data in memory 1 can be easily performed from a device other than the interrogator once the protocol of the data communication with the interrogator is decoded, therefore the security cannot be guaranteed.
Hence an object of the present invention is to provide a non contact type IC card allowing the prevention of rewriting of a storage region in which data requiring security is stored.
Another object of the present invention is to provide a highly reliable non contact type IC card through the control of rewriting of the storage region in which data requiring security is stored.
A non contact type IC card according to the present invention is responsive to externally applied data for performing data communication, and includes: a first storing circuit storing data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; a control circuit controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the data; a selection circuit selecting whether the data is to be written into the location in the first storing circuit designated by the control circuit; and a state setting circuit controlling the selection by the selection circuit, the data is written into the location in the first storing circuit designated by the control circuit when the state setting circuit is in a first state, whereas, the data is inhibited from being written into the first storing circuit designated by the control circuit when the state setting circuit is in a second state other than the first state.
In another aspect of the present invention, a non contact type IC card is responsive to externally applied data for performing data communication, and includes: a first storing circuit storing the data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; a control circuit controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the data; a detection circuit receiving a control signal from the control circuit and giving instruction for controlling a state of the first storing circuit; and a selection circuit receiving the instruction of the detection circuit and selecting whether the data is to be written into the location of the first storing circuit designated by the control circuit; and the control signal output from the control circuit indicates whether the first storing circuit is in a data rewriting permitted state or a data rewriting inhibited state; and the data is written into the location in the first storing circuit designated by the control circuit when the detection circuit detects that the first storing circuit is in the data rewriting permitted state, whereas the data is not written into the location in the first storing circuit designated by the control circuit when the detection circuit detects that the first storing circuit is in the data rewriting inhibited state.
In still another aspect of the present invention, a non contact type IC card performs a data communication based on an externally applied radio wave signal, and includes: a receiving circuit receiving the radio wave signal; a first storing circuit storing the data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; a control circuit generating the data based on the radio wave signal received at the receiving circuit and controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the generated data; a detection circuit detecting a frequency of the radio wave signal received by the receiving circuit; and a selection circuit selecting whether the data is to be written into the location in the first storing circuit designated by the control circuit based on a result of the detection by the detection circuit; and wherein the data is written into the location in the first storing circuit designated by the control circuit, when the receiving circuit receives the radio wave signal and the frequency of the radio wave signal is detected to be a first frequency by the detection circuit, whereas the data is not written into the location in the first storing circuit designated by the control circuit when the frequency of the radio wave signal is detected to be a second frequency other than the first frequency by the detection circuit.
In still another aspect of the present invention, a non contact type IC card is responsive to externally applied data for performing data communication, and includes: a first storing circuit storing the data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; a control circuit controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the data; and a data fixing circuit receiving the data to be written into the location in the first storing circuit designated by the control circuit and supplying a particular data; and wherein a value of the predetermined data supplied from the data fixing circuit is a value determined by an initial state of the first storing circuit, and wherein only the particular data supplied from the data fixing circuit is written into the location in the first storing circuit designated by the control circuit.
In still another aspect of the present invention, a non contact type IC card is responsive to externally applied data for performing data communication, and includes: a first storing circuit storing said data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; a control circuit controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the data; a selection circuit selecting whether the data is to be written into the location in the first storing circuit designated by the control circuit; and a state setting circuit controlling the selection by the selection circuit; and wherein the data is written into the location in the first storing circuit designated by the control circuit when the state setting circuit is in a first state, whereas, the data is written into a location other than the location in the first storing circuit designated by the control circuit when the state setting circuit is in a second state other than the first state.
In still another aspect of the present invention, a non contact type IC card is responsive to externally applied data for performing data communication, and includes: a first storing circuit storing the data requiring security; a second storing circuit storing data other than the data to be stored in the first storing circuit; and a control circuit controlling for writing the data into a location in one of the first storing circuit and the second storing circuit according to a content of the data; and wherein the first storing circuit allows rewriting of a predetermined times.
Therefore a main advantage of the present invention lies in the prevention of falsification of storage contents through the control of rewriting of data stored in a storage portion storing data requiring security.